The present embodiment relates generally to methods and cement compositions for sealing a subterranean zone penetrated by a wellbore.
In the drilling and completion of an oil or gas well, a cement composition is often introduced in the wellbore for cementing pipe string or casing. When the desired drilling depth of the well is reached, a cement composition is pumped into the annular space between the walls of the wellbore and the casing. In this process, known as “primary cementing”, the cement composition sets in the annular space, supporting and positioning the casing, and forming a substantially impermeable barrier, or cement sheath, which isolates the wellbore from subterranean zones. It is understood that the performance of the cement composition is important to achieving and maintaining zonal isolation. Throughout the life of a well, especially if zonal isolation is comprised, secondary cementing operations, such as remedial cementing and repairs to existing cemented areas, will be performed on the well.